The new German guideline for capacity of unsignalized intersections

This paper describes the background of a new German guideline for the estimation of the capacity at unsignalized intersections. It contains information on fundamental aspects of the theory as well as a description of the proposed procedure which results from several research projects carried out on behalf of the West German Federal Minister of Transport. The new guideline will be a revision of the German procedure introduced in 1972, which has been transferred as chapter 10 of the Highway Capacity Manual (HCM) in 1985. Some of the unsolved problems being identified have now been solved based on simulation studies. The new guideline has also been developed in close contact with the HCM-subcommittee for unsignalized intersections. According to this more emphasis has been put on the estimation of delays. The new guideline again has the concept of a paper-and-pencil-method. However, for getting more realistic results the application of the KNOSIMO-simulation tool is recommended for practical use. Both methods have successfully been tested with a series of realistic cases obtained from practice.